Ampere rated reed switch

ABSTRACT

A reed switch encapsulated within a non-magnetic, electrically non-conductive housing and having first and second integrally formed ferromagnetic members extending from positions externally of said housing through opposite ends of said housing to within a chamber in said housing such that those ends of said members within said chamber overlap and form a gap therebetween when the switch is in the deactivated position. Each of the members have a constricted section adjacent the respective end of the housing so as to enable the ends of the members within the housing to bend toward each other and into engagement when the switch is activated by the application of a magnetic field thereto.

[4 June 18, 1974 1 AMPERE RATED REED SWITCH [75] Inventor: Robert Charles Guichard, Normal,

Ill.

[73] Assignee: General Electric Company, New

York, NY.

[22] Filed: Mar. 29, 1973 [21] Appl. No.: 345,997

[52] US. Cl. 335/154, 200/144 B, ZOO/148 G I [51] Int. Cl. H0lh 1/66, HOlh 51/28 [58] Field of Search 335/151, 154; ZOO/166 C, ZOO/166 J, 144 B; 29/622 OTHER PUBLICATIONS Lafrate et a1,, Reed Switch, IBM Technical Disclosure Bulletin, January 1970, p. 1213.

Primary Examiner-Robert K. Schaffer Assistant Examiner-William J. Smith Attorney, Agent, or Firm-S. A. Young; P. L. Schlamp; F. L. Neuhauser 1 1 ABSTRACT A reed switch encapsulated within a non-magnetic. electrically non-conductive housing and having first and second integrally formed ferromagnetic members extending from positions externally of said housing through opposite ends of said housing to within a chamber in said housing such that those ends of said members within said chamber overlap and form a gap therebetween when the switch is in the deactivated position. Each of the members have a constricted section adjacent the respective end of the housing so as to enable the ends of the members within the housing to bend toward each other and into engagement when the switch is activated by the application of a magnetic field thereto. I

15 Claims, 3 Drawing Figures 1 AMPERE RATED REED SWITCH BACKGROUND OF THEINVENTION 1. Field Of The Invention This invention relates to reed switches and more particularly to high powered sealed contact relays.

2. Description Of The Prior Art Quite often in prior art magnetically operable sealed relays, otherwise known as reed switches, the external switch terminal leads are made of suitable metal which readily and conveniently form a good quick glass to metal seal to the glass housing. These external leads, which are often made of a good electrically conductive material, extend into a chamber within the housing and form contact terminals therewithin. Movable magnetic members, which comprise the switching contacts, are mechanically coupled to these terminals. In some cases the magnetic members are directly attached to these terminals, and in other arrangements an intermediate shim is used to connect the magnetic member to the terminal. It is time consuming and expensive to directly connect the magnetic member to the terminal, inasmuch as the materials are basically dissimilar. It is also time consuming and expensive to connect the magnetic member and the contact terminal directly to an intermediate shim. Furthermore, since the contact terminal and the shim are made of non-magnetic material, the magnetic flux path within the encapsulated housing often varies depending upon the actual positioning of the reed member within the housing. This variation in flux path requires the use of a larger coil for producing the necessary magnetic flux to insure actuation of the switch upon the occurence of worst case tolerances.

Another problem associated with prior art reed switches occurs when overlapping surfaces of two reed members within the housing form high resistance interfacing surfaces because of arcing between the surfaces when these surfaces are separated during deactivation of the switch. The high resistance interfacing surfaces are also formed by the wear caused by repeated contact of the surfaces upon activation. Furthermore the interfacing surfaces often have a tendency to slowly separate upon discontinuation of the magnetic field which is applied to the switch because of the effect of residual magnetism at the interfacing surfaces.

Still further some reed switches have flat contact buttons which wear at the corners in an uneven fashion, thereby causing an early wearing out of the switch.

Still further problems also associated with reed switches often result from a gaseous atmosphere within the switch having an active component therewithin. This actived gaseous component can often result in oxidizing of the contact and overlapping magnetic surfaces due to arcing when the switch is being deactivated. Still further if the molecular weight of the gaseous components within the housing is relatively high the heat dissipation from within the housing likewise is often relatively slow, thereby creating a heat build-up within the device and thus limiting the power rating of the device.

OBJECTS OF THE INVENTION It is therefore an object of this invention to provide an improved reed switch having none of the disadvantages mentioned hereinabove.

Another object of this invention is to provide a reed switch which has a fixed and predetermined magnetic flux path therewithin so as to lower the burden on the coil used to form the magnetic field during activation of the switch.

Another object of this invention is to reduce the number of components required in a power reed switch.

Another object of this invention is to provide a reed switch having an internal atmosphere therewithin which quickly dissipates heat generated within the housing without adversely-affecting operating voltage levels of the switch.

Another object of this invention is to improve the speed of separation of the reed members when the switch is deactivated, by reducing the residual magnetism at the interfacing surfaces of the reed members.

Another object of this invention is to improve the wear resistance and lower the ohmic resistance of the overlapping interfacing surfaces of the reed members.

vA further object of this invention is to prevent contacts within the housing of the switch from wearing unevenly at the corners thereof.

Other objects of the invention will be pointed out and understood hereinafter.

SUMMARY OF THE INVENTION In accordance with a broad aspect of the invention there is provided a reed switch having movable integrally formed longitudinally extending magnetic members, wherein each member has one end positioned outside of a housing and another end extending within the housing so that the internal ends of each of the two members overlap and form opposing surfaces therebetween. The opposing surfaces are separated by a gap when the switch is not activated and are in contact when the switch is activated. Upon activation of the switch the magnetic members move toward each other and the overlapping surfaces become engaged. Each of the overlapping surfaces of the magnetic members are coated witha vacuum or sputtered deposition of rhodium to increase the wear resistance of the interfacing surfaces, to lower their ohmic resistance, and also to reduce the residual magnetism therebetween and thus allowing for quicker disengagement of the reed members upon deactivation of the switch. A silver leaf cantilever spring is fastened at one end to the underside of one of the magnetic members, and the free end of the spring extends beyond the interior end of the magnetic member. A first relatively low ohmic resistance contact is provided on the free end of the leaf spring, and a second contact of like material is provided on the adjacent underlying surface of the other magnetic member and in juxtaposition with the first contact, whereby the first and second contacts are separated by a gap which is approximately half the length of the gap separating the overlapping opposing surfaces of the magnetic members when the switch is not activated. Upon activation of the switch, the first and second contacts become engaged prior to the engagement of the overlapping opposing surfaces of themembers, and when the switch is deactivated the opposing surfaces of the magnetic members disengage first before the adjoining surfaces of the contacts disengage so as to substantially confine arcing prior to activation and immediately preceeding deactivation of the switch to the contact surfaces rather than the interfacing magnetic surfaces.

According to a feature of the invention the gaseous atmosphere within the housing is comprised of approximately 80 percent or more by volume of helium or hydrogen and approximately 20 percent or less by volume of sulphur hexafluoride.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of the power reed switch according to the invention while the switch is in the deactivated condition;

FIG. 2 is an enlarged fragmentary front view of the switch shown in FIG. 1 including the contacts and overlapping and opposing portions of the surfaces of the magnetic members; and

FIG. 3 is a front view of the power reed switch when activated.

DESCRIPTION OF A PREFERRED EMBODIMENT Details of the invention will now be explained with reference to FIGS. 1-3.

A power reed switch has a set of switching contacts located within a hermetically sealed chamber 12 of an insulative housing 14 preferably formed of glass or any other suitably transparent insulative material. Chamber 12 contains an atmosphere which will suppress arcing between the contacts within the chamber, dissipate heat as rapidly as possible so as to increase the current and power handling capabilities of the switch, and afford a desired voltage breakdown characteristic. The gaseous atmosphere within the chamber of previous devices comprised nitrogen as a gaseous constituency. However inasmuch as helium and hydrogen have a much lower atomic weight than nitrogen, they provide a better'medium for dissipating heat from the chamber than does nitrogen. Furthermore helium and hydrogen also have a tendency to suppress arcing within the device better than nitrogen. I-Ielium or hydrogen if used alone as a gaseous constituent would have poor voltage breakdown characteristics due. to their low atomic weight. Therefore a gaseous constituent of sulphur hexafluoride is also present in the chamber so as to prevent a low voltage'breakdown of the gaseous atmosphere within the chamber. However if more than approximately percent by volume of sulphur hexafluoride is present within the chamber, the heat dissipating characteristics of the gaseous medium begin to degenerate sharply. Therefore the gaseous atmosphere within the chamber should contain approximately 80 percent or more by volume of helium and/or hydrogen and approximately 20 percent or less by volume of sulphur hexafluoride for satisfactory performance.

Switch 10 is further comprised of switching means formed by a first single piece conductive member 16 and a second single piece conductive member 18 extending longitudinally from opposite ends of the housing. Members 16 and 18 are each integrally formed from a suitable ferromagnetic alloy such as (by way of example only) 52 percent nickel and 48 percent iron. Member 16 comprises an external terminal 20, a portion 22 sealed in one end 24 of housing 14, a portion 26 of reduced cross section adjacent portion 22 within chamber 12 of the housing, and a main portion 28 adjacent portion 26 extending toward the center of the chamber of the housing. Similarly member 18 has a terminal 30 extending externally from the other end 32 of housing 14. a portion 34 sealed in the end wall 32 of housing 14, portion 36 of reduced cross section adja cent portion 34 within chamber 12, and a main portion 38 adjacent portion 36 extending toward the center of chamber 12. An end 40 of main portion 28 of member 16 overlaps an end 42 of main portion 38 of member 18 so as to form respective overlapping opposed sections 44 and 46 therebetween.

During activation the opposed sections 44 and 46 engage and in order to prevent surface wear of overlapping sections 44 and 46 caused by continuous opening and closing of the switch, respective sections 44 and 46 are provided with respective coatings 48 and 50 of wear resistant material. This material is of high conductivity and is effective for minimizing arcing between sections 44 and 46 immediately before and just after they are in engagement. Still further, coatings 48 and 50 cause the switching speed of the device to increase by reducing the residual surface magnetism of the overlapping sections 44 and 46, thereby allowing the overlapping sections to disengage more rapidly when the switch is deactivated. One such material which is effective for this purpose is rhodium. The rhodium coatings preferably are either vacuum or sputter deposited rather than plated onto sections 44 and 46. If coatings 48 and 50 were plated rather than vacuum or sputter deposited onto respective sections 44 and 46, the resulting coatings would be unnecessarily thick and would use more of the expensive rhodium material and thus increase the cost of the device. The typical thickness of coatings 48 and 50 is approximately forty millionth of an inch, although this thickness can vary depending upon design requirements and needs. For example, a typical variation range can be from approximately twenty millionths to one hundred millionths of an inch.

The portions 26 and 36 of respective members 16 and 18 are so dimensioned that ends 40 and 42 of respective main portions 28 and 38 bend toward one another when the magnetic lines of flux of the magnetic field pass through members 16 and 18 and bridge the air gap between sections 44 and 46 forcing their mutual attraction until they become engaged. By way of example only, portions 26 and 36 and main portions 28 and 38 are of rectangular cross section and the width of portions 26 and 36 correspond to thewidth of main portions 28 and 38. The portions 26 and 36 can be approximately half the thickness of main portions 28 and 38, and approximately one fourth the thickness of adjacent portions 22 and 34. While these relative dimensions enable the main portions 28 and 38 to flex together and apart, other reasonably designed dimensions are just as suitable.

A leaf spring 52 has one end 54 attached to main portion 38 of member 18 at a point adjacent constricted portion 36 by a rivet 56. Rivet 56 can be a nickel/iron member that has its head portion 58 welded to the top surface of main portion 38. The other end 60 of leaf spring 52 extends in a cantilever fashion beyond inner end 42 of member 18 and has a contact button 62 affixed thereto. A similar contact button 64 is affixed to the under surface of main portion 28 and engages contact button 62 when the switch is activated. Contact buttons 62 and 64 can be made of a suitable refractory conductive material which is either deposited, welded or otherwise respectively attached to spring 52 and main portion 28 using standard techniques. By way of example only, contact buttons 62 and 64 can be comprised of approximately 85 percent by weight of silver and percent by weight of nickel. The contact buttons are comprised of a large percentage of silver so that the alloyed buttons have good electrical conductivity characteristics. Nickel is added to the alloy to increase the hardness of the contact buttons and reduce the wear of their surfaces as they move into engagement with one another.

Members 16 and 18, leaf spring 52 and contacts 62 and 64 are so positioned within chamber 12 and are so designed that when the switch is not actuated, coatings 48 and 50 on respective sections 44 and 46 are separated by a gap which is at least twice as great as the gap which separates contact buttons 62 and 64. These gap conditions are designed to insure that, when the switch is actuated and ends and 42 of respective members 16 and 18 move toward one another, contact buttons 62 and 64 become engaged prior to the engagement of coatings 48 and 50 so that if arcing should occur, it would be restricted to the area around contact buttons 62 and 64. This reduces the chances of arcing between coatings 48 and 50 and thereby minimizes the chances of any surface alteration of the ends of the reed members so as to lessen the shifting or degeneration of the switching characteristics of the device over its lifetime.

As shown in FIG. 3, when the switch is activated and contacts 62 and 64 become engaged, that portion of leaf spring 52 adjacent end 42 of member 18 moves away from member 18. Now when the switch is deactivated or opened by removal of the magnetic field from the proximity of members 16 and 18, end coatings 48 and 50 disengages, and as end 42 of member 18 continues to move away from end 40 of member 16, that portion of member 18 adjacent end 42 contacts leaf spring 52 in a hammering motion, so as to facilitate the disengagement of contacts 62 and 64 from one another. The extent of this hammering motion is due to the fact that main portion 38 of member 18 is a much greater mass than the mass of leaf spring 52. Therefore, if there is any tendency of contacts 62 and 64 to become welded together, this above described hammering motion breaks any welded joints formed therebetween so as to prevent failure of the switch due to contact sticking. Leaf spring 52 can be made of silver. Silver is chosen because it has a good modulus of elasticity, so as to insure that leaf spring 52 will always return to its exact initial position after the switch has been deactivated. That portion 66 of the leaf spring 52, which supports contact button 62, is bent slightly upward from the remainder of leaf spring 52 in order to insure that the portion of leaf spring 52 adjacent end 42 of member 18 will actually move away from the adjacent end 52 when contact 62 engages contact 64. The contacting surfaces of respective contacts 62 and 64 have radius of curvatures such that the contacts are thickest at their center. This insures that the contacts will engage each other at their center and thickest portions so as to confine the wear of the contacts to their thickest portions, thereby prolonging the life of the switch.

It should be noted that constricted portions 26 and 36 are so formed that the top and bottom surfaces thereof are flat in order to control the plane of alignment of ends 40 and 42 as these ends flex toward and away from one another. Furthermore main portions 28 and 38 of respective members 16 and 18 also have their top and bottom surfaces made flat in order that they may more easily accommodate the appropriate contact buttons and leaf spring, and also provide a larger intersurface contact area for coatings 48 and 50 so that the interface therebetween has a low ohmic resistance.

Housing 14 should be preferably made of a glass which will form a good glass to metal seal with portions 22 and 34 of respective members 16 and 18 so that the switch held within chamber 12 is hermetically sealed from the atmosphere. The glass used should match the thermal coefiicient of expansion of the metal members at least up to the sealing temperature between the glass and the metal member. A glass, which has a thermal coefficient of expansion that matches the thermal coefficient of expansion of the ferromagnetic alloy used for members 16 and 18 at least up to the sealing temperature between the glass and metal, is a lead free infrared absorbing glass sold by Owens Illinois. By using this infrared absorbing glass, the heat absorption at the point the glass to metal seal is to be formed is increased, and the sealing time actually decreases by the factor of five to ten times. In this instance the glass to metal seal is formed just approximately below 1,000 C. The actual positioning and assembling of the magnetic members and their associated parts in chamber 12, and the subsequent sealing of portions 22 and 34 to respective ends 24 and 32 of glass housing 14 are performed using well known standard manufacturing techniques.

Although the invention has been described with reference to a specific embodiment thereof, numerous modifications are possible without departing from the invention and it is desirable to cover all modifications falling within the spirit and scope of this invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A sealed switch actuated by an externally applied magnetic field comprising:

a. a hermetically sealed housing formed of nonmagnetic non-conductive lead-free infrared ab-' sorbing glass;

b. a first single piece integrally formed electrically conducting magnetic member having a terminal.

portion positioned externally of an adjacent one end of said end of said housing, a section passing through and sealed in said one end of said housing, and a portion located in said housing;

0. a second single piece integrally formed electrically conducting magnetic member having a terminal portion positioned externally of and adjacent the other end of said housing, a section passing through and sealed in the other end of said housing, and a portion located in said housing;

(1. said glass housing having a thermal coefficient of expansion approximating that of said first and second magnetic members;

e. respective ends of said portions of said first and second members in said housing being in juxtaposition and separated by a gap when said switch is deactivated; and

f. means for allowing said portions of said first and second members in said housing to bend toward one another until the respective overlapping ends engage one another upon activation of the switch by the application of the magnetic field thereto.

2. A switch according to claim 1, wherein said engage means includes said first member having a portion of reduced cross section adjacent one end of and in said housing to allow said first member to bend toward said second member upon the application of a magnetic field thereto.

3. A switch according to claim 2, wherein said engage means further includes the other said member having a portion of reduced cross section adjacent the other end of and in said housing for allowing that end of said other member within said housing to bend toward said one member upon the application of a magnetic field thereto.

4. A switch according to claim 1, wherein said first and second members are comprised of a ferromagnetic material.

5. A switch according to claim 1, wherein the juxtaposed ends of said members form opposed overlapping surfaces, and each overlapping surface includes thereon a coating of wear-resistant electrically conductive non-magnetic material to improve the speed of disengagement of said first and second members when the switch is deactivated.

6. A switch according to claim 5, wherein said coating is comprised of a deposition of rhodium having a layer thickness ranging between approximately twenty and one hundred millionths of an inch.

7. A switch according to claim 6, wherein the thickness of said rhodium coating is approximately forty millionths of an inch.

8. A switch according to claim 1, wherein the atmosphere within said housing is comprised of approximately 80 percent or more by volume of helium and hydrogen, and approximately 20 percent or less by volume of sulphur hexafluoride.

9. A switch according to claim 1, wherein the atmosphere within said housing is comprised of approximately 80 percent or more volume of helium or hydrogen, and approximately 20 percent or less by volume of sulphur hexafluoride.

10. A switch according to claim 1, further comprising a cantilevered leaf spring having one end thereof firmly attached to that surface of said second member opposite the surface adjacent the gap between the first and second members, said leaf spring extending flush against and along the surface of said second member and past that end of said second member which is in said housing, the other end of said leaf spring having a first contact attached thereto said first contact being spaced adjacent said first member, said first member having another contact attached thereto overlying and in juxtaposition with said first contact.

11. A switch according to claim 10, wherein said first and second contacts are separated by a gap approximately twice as small as the gap separating the overlapping ends of said first and second magnetic members.

12. A switch according to claim 11 wherein said first and second contacts are comprised of an alloy of approximately 85 percent silver by weight and approximately 15 percent nickel by weight.

13. A switch according to claim 12, wherein said leaf spring is comprised of silver.

14. A sealed switch actuated by an externally applied magnetic field comprising:

a. a hermetically sealed housing, formed of nonmagnetic non-conductive material, having an atmosphere therewithin comprised of approximately percent or more by volume of helium and hydrogen, and approximately 20 percent or less by volume of sulfur hexafluoride;

b. a first single piece integrally formed electrically conducting magnetic member having a tenninal portion positioned externally of and adjacent one end of said housing, a section passing through and sealed in said one end of said housing, and a portion located in said housing;

c. a second single piece integrally formed electrically conducting magnetic member having a portion positioned externally of and adjacent the other end of said housing, a section passing through and sealed in the other end of said housing, and a portion located in said housing;

d. respective ends of said portions of said first and second members in said housing being in juxtaposition and separated by a gap when said switch is deactivated; and v e. means for allowing said portions of said first and second members in said housing to bend toward one another until the respective overlapping ends engage one another upon activation of the switch by the application of the magnetic field thereto.

15. A sealed switch actuated by an externally applied magnetic field comprising:

a. a hermetically sealed housing, formed of nonmagnetic non-conductive material, having an atmosphere therewithin comprised of approximately 80 percent or more by volume of helium or hydrogen, and approximately 20 percent or less by volume or sulfur hexafluoride;

b. a first single piece integrally formed electrically conducting magnetic member having a terminal portion positioned externally of and adjacent one end of said housing, a section passing through and sealed in said one end of said housing, and a portion located in said housing;

c. a second single piece integrally formed electrically conducting magnetic member having a terminal portion positioned externally of and adjacent the other end of said housing, a section passing through and sealed in the other end of said housing, and a portion located in said housing;

d. respective ends of said portions of said first and second members in said housing being in juxtaposition and separated by a gap when said switch is deactivated; and

e. means for allowing said portions of said first and second members in said housing to bend toward one another until the respective overlapping ends engage one another upon activation of the switch by the application of the magnetic field thereto.

2 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3,818,392 Dated June 18, 1974 Inventofls) Robert C. Guichard It is certified that error appears in the above-identifid-yatent v and that said Letters Patent are hereby corrected as shown below:

Claim. 1, line 10 1 after "said" (first occurrence) i delete end of said Claim l4, line -16, after "having a" insert terminal Claim 15 line 8', before "su1fur' delete "or" 'and insert of Signed and sealed this 29th day of October 1974,

(SEAL) -A'ttest: a I

McCOY M. mason JR. 0. MARSHALL D'ANN Attesting Officer 1 Commissioner of Patents 222 3 UNITED STATES PATENT OFFICE CERTIFICATE OF-CORRECTION Patent No. 3,818,392 I Dated June 18, 1974 Inventor(s) Robert C. Gnichard It is certified that error appears in the above identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Claim 1, line 10 I after "said" (first occurrence) delete end of said Claim 14, line 16, after "having a" insert terminal Claim line before "sulfur" delete "or" and I insert of Signed and sealed this 29th day of October 1974a (SEAL) Attest:

MCCOY M. GIBSON JR. 0. MARSHALL DANNE Attesting Officer Commissioner of Patents 

1. A sealed switch actuated by an externally applied magnetic field comprising: a. a hermetically sealed housing formed of non-magnetic nonconductive lead-free infrared absorbing glass; b. a first single piece integrally formed electrically conducting magnetic member having a terminal portion positioned externally of an adjacent one end of said end of said housing, a section passing through and sealed in said one end of said housing, and a portion located in said housing; c. a second single piece integrally formed electrically conducting magnetic member having a terminal portion positioned externally of and adjacent the other end of said housing, a section passing through and sealed in the other end of said housing, and a portion located in said housing; d. said glass housing having a thermal coefficient of expansion approximating that of said first and second magnetic members; e. respective ends of said portions of said first and second members in said housing being in juxtaposition and separated by a gap when said switch is deactivated; and f. means for allowing said portions of said first and second members in said housing to bend toward one another until the respective overlapping ends engage one another upon activation of the switch by the application of the magnetic field thereto.
 2. A switch according to claim 1, wherein said engage means includes said first member having a portion of reduced cross section adjacent one end of and in said housing to allow said first member to bend toward said second member upon the application of a magnetic field thereto.
 3. A switch according to claim 2, wherein said engage means further includes the other said member having a portion of reduced cross section adjacent the other end of and in said housing for allowing that end of said other member within said housing to bend toward said one member upon the application of a magnetic field thereto.
 4. A switch according to claim 1, wherein said first and second members are comprised of a ferromagnetic material.
 5. A switch according to claim 1, wherein the juxtaposed ends of said members form opposed overlapping surfaces, and each overlapping surface includes thereon a coating of wear-resistant electrically conductive non-magnetic material to improve the speed of disengagement of said first and second members when the switch is deactivated.
 6. A switch according to claim 5, wherein said coating is comprised of a deposition of rhodium having a layer thickness ranging between approximately twenty and one hundred millionth''s of an inch.
 7. A switch according to claim 6, wherein the thickness of said rhodium coating is approximately forty millionth''s of an inch.
 8. A switch according to claim 1, wherein the atmosphere within said housing is comprised of approximately 80 percent or more by volume of helium and hydrogen, and approximately 20 percent or less by volume of sulphur hexafluoride.
 9. A switch according to claim 1, wherein the atmosphere within said housing is comprised of approximately 80 percent or more volume of helium or hydrogen, and approximately 20 percent or less by volume of sulphur hexafluoride.
 10. A switch according to claim 1, further comprising a cantilevered leaf spring having one end thereof firmly attached to that surface of said second member opposite the surface adjacent the gap between the first and second members, said leaf spring extending flush against and along the surface of said second member and past that end of said second member which is in said housing, the other end of said leaf spring having a first contact attached thereto said first contact being spaced adjacent said first member, said first member having another contact attached thereto overlying and in juxtaposition with said first contact.
 11. A switch according to claim 10, wherein said first and second contacts are separated by a gap approximately twice as small as the gap separating the oveRlapping ends of said first and second magnetic members.
 12. A switch according to claim 11 wherein said first and second contacts are comprised of an alloy of approximately 85 percent silver by weight and approximately 15 percent nickel by weight.
 13. A switch according to claim 12, wherein said leaf spring is comprised of silver.
 14. A sealed switch actuated by an externally applied magnetic field comprising: a. a hermetically sealed housing, formed of non-magnetic non-conductive material, having an atmosphere therewithin comprised of approximately 80 percent or more by volume of helium and hydrogen, and approximately 20 percent or less by volume of sulfur hexafluoride; b. a first single piece integrally formed electrically conducting magnetic member having a terminal portion positioned externally of and adjacent one end of said housing, a section passing through and sealed in said one end of said housing, and a portion located in said housing; c. a second single piece integrally formed electrically conducting magnetic member having a portion positioned externally of and adjacent the other end of said housing, a section passing through and sealed in the other end of said housing, and a portion located in said housing; d. respective ends of said portions of said first and second members in said housing being in juxtaposition and separated by a gap when said switch is deactivated; and e. means for allowing said portions of said first and second members in said housing to bend toward one another until the respective overlapping ends engage one another upon activation of the switch by the application of the magnetic field thereto.
 15. A sealed switch actuated by an externally applied magnetic field comprising: a. a hermetically sealed housing, formed of non-magnetic non-conductive material, having an atmosphere therewithin comprised of approximately 80 percent or more by volume of helium or hydrogen, and approximately 20 percent or less by volume or sulfur hexafluoride; b. a first single piece integrally formed electrically conducting magnetic member having a terminal portion positioned externally of and adjacent one end of said housing, a section passing through and sealed in said one end of said housing, and a portion located in said housing; c. a second single piece integrally formed electrically conducting magnetic member having a terminal portion positioned externally of and adjacent the other end of said housing, a section passing through and sealed in the other end of said housing, and a portion located in said housing; d. respective ends of said portions of said first and second members in said housing being in juxtaposition and separated by a gap when said switch is deactivated; and e. means for allowing said portions of said first and second members in said housing to bend toward one another until the respective overlapping ends engage one another upon activation of the switch by the application of the magnetic field thereto. 